Animal Kingdom

• Porifera (sponges)

  • includes organisms that lack specialized digestive, nervous, and respiratory systems.
  • These organisms have a radial symmetry, do not possess a coelom, and do not show any segmentation.
  • These organisms either have numerous tiny pores called ostia or larger pores called Oscula which are less in number.
  • The function of these pores is to allow the circulation of water. The members of Phylum Porifera are non-motile and are fixed to a substratum.
• Ostia - tiny pores
• Oscula/Osculum - larger pores
• Characteristics of Porifera:

  • Present in both marine and freshwater sources
  • Bodies are unevenly and loosely arranged
  • They are cylindrical and have a cellular level of organization
  • The sponge is supported and shielded by spicules Reproduces asexually via fragmentation or budding
  • The cavity present inside the body is known as spongocoel
  • Take food via a Holozoic mode of nutrition
  • Exhibit a high rate of regeneration
  • Reproduction involves internal fertilization
  • Hermaphrodites
  • Respiration and excretion occur via diffusion
  • These organisms are ammonotelic
• Classification:

  1. Calcarea
  2. Hexactinellids
  3. Demospongiae
• Examples:

  • Scypha: Calcarea
  • Euplectella: Hexactinellids
  • Spongilla: Desmospongiae
• Cnidaria (Coelenterata)

  • The name Cnidaria comes from the Greek word "cnidos, " which means stinging nettle.
  • Casually touching many cnidarians will make it clear how they got their name when their nematocysts eject barbed threads tipped with poison.
• Cnidaria (Coelenterata)

  • Coelenterates have specialized cells known as cnidoblasts that bear stinging structures known as nematocysts.
  • These aid in the capture of prey by paralyzing them with a poison injection.
  • They are also known as cnidarians due to the presence of cnidoblasts
• Characteristics of Cnidaria

  • Have a hollow body cavity.
  • The body is differentiated into two ends. Includes all aquatic animals.
  • The body is made of two layers of cells: inner and outer linings.
  • Live in colonies (corals) as well as solitary (Sea anemone).
  • Cnidarians exhibit radial symmetry.
• Characteristics of Cnidaria:

  • All cnidarians are carnivores.
  • Cnidarian tentacles have organelles called nematocysts that eject venomous filaments into prey.
  • Cnidarians go through sexual and asexual reproductive phases.
  • Cnidarians exist as free-swimming medusae or stationary polyps.
  • They may exist as both forms over the course of their lives.
• Examples:

  • Jellyfish: Scyphozoa
  • Sea Anemones: Anthozoa
  • Coral: Anthozoa
• Platyhelminthes

  • Phylum Platyhelminthes belongs to the kingdom Animalia.
  • This phylum includes 13,000 species. The organisms are also known as flatworms.
  • These are acoelomates and they include many free-living and parasitic life forms.
• Characteristics of Platyhelminthes

  • Triploblastic, acoelomate, and bilaterally symmetrical.
  • Can be free-living or parasitic.
  • The body has a soft covering with or without cilia.
  • Their body is dorsoventrally flattened without any segments and appears like a leaf.
  • They are devoid of the anus and circulatory system but have a mouth.
  • They respire by simple diffusion through the body surface.
• Characteristics of Platyhelminthes

  • They have an organ level of organization.
  • They do not have a complete digestive tract.
  • The space between the body wall and organs is filled with connective tissue parenchyma which helps in transporting the food material.
  • They are hermaphrodites, i.e., both male and female organs are present in the same body.
  • They reproduce sexually by fusion of gametes and asexually by fission and regeneration.
  • Fertilization is internal.
• Examples:

  • Planaria - Turbellaria
  • Schistosoma - Trematoda
  • Taenia Solium - Cestoda
• Annelida

  • Phylum Annelida is a very broad phylum belonging to the kingdom Animalia.
  • The Annelids are found in aquatic as well as terrestrial environments.
  • These are bilaterally symmetrical invertebrate organisms.
  • Their segmented body distinguishes them from any other organism.
• Characteristics of Annelida:

  • The Annelids are triploblastic, coelomate, and bilaterally symmetrical.
  • They exhibit organ system level organization.
  • Their body is segmented.
  • They respire through their general body surface.
  • Excretory and nervous systems are present. Nephridia are the excretory organs.
  • They have a well-developed circulatory and digestive system.
  • Their body contains hemoglobin, which gives them a red color.
• Characteristics of Annelida

  • Regeneration is a very common characteristic of the Annelids.
  • They have parapodia and chitinous setae, used for locomotion.
  • They live in moist environments, moist soil, freshwater and marine water.
  • Most of the Annelids are hermaphrodite, i.e., male and female organs are present in the same body.
  • They reproduce both sexually and asexually.
  • Fertilization can be internal or external.
• Examples:

  • Nereis - Polychaeta
  • Pheremita - Oligochaeta
  • Leeches - Hirundinea
• Nematoda

  • From Superphylum Ecdysozoa - name derives from the word ecdysis, which refers to the shedding, or molting, of the exoskeleton
  • Also called roundworms, are found in most aquatic habitats, in the soil, in the moist tissues of plants, and in the body fluids and tissues of animals.
  • While 28,000 species are known, perhaps 20 times that number actually exist.